Regulation of gene expression is achieved by the direct or indirect interaction of regulatory proteins such as transcription factors with cis-acting DNA regulatory regions, including promoters, promoter elements, and promoter motifs, which may be located upstream, downstream, and/or within a gene of interest. Certain regulatory proteins can interact with regulatory regions for a number of genes, often driving the coordinate expression of multiple genes in a pathway. For example, binding of a transcription factor to a promoter or promoter element usually results in a modulation, e.g., an increase, of basal rates of transcription initiation and/or elongation. Promoters typically have a modular organization that includes multiple cis-elements (promoter elements), which can interact in additive or synergistic manners to modulate transcription. Identification of regulatory proteins that bind to particular DNA regulatory regions can provide tools to facilitate the selective expression of proteins of interest, e.g., to modify plant biosynthetic pathways.
Plant families that produce alkaloids include the Papaveraceae, Berberidaceae, Leguminosae, Boraginaceae, Apocynaceae, Asclepiadaceae, Liliaceae, Gnetaceae, Erythroxylaceae, Convolvulaceae, Ranunculaeceae, Rubiaceae, Solanaceae, and Rutaceae families. Many alkaloids isolated from such plants are known for their pharmacologic (e.g., narcotic), insecticidal, and physiologic effects. For example, the poppy (Papaveraceae) family contains about 250 species found mainly in the northern temperate regions of the world. The principal morphinan alkaloids in opium poppy (Papaver somniferum) are morphine, codeine, and thebaine, which are used directly or modified using synthetic methods to produce pharmaceutical compounds used for pain management, cough suppression, and addiction.